During the secondary treatment of sewage, which of the following change in the effluent occur due to flocs?
- ✓Reduction in BOD
- BIncrease in BOD
- CDecrease in DO
- DNo change in DO or BOD
Answer: A.
View full solution →Question types
MODEL PAPER 2025 question types
40 questions across 6 question groups — pick any mix to generate a BIOLOGY paper with step-by-step answer keys.
40
Questions
6
Question groups
5
Question types
01
M.C.Q (1 Marks)
13 Q→022 Marks Questions
8 Q→033 Marks Question
7 Q→045 Marks Questions
6 Q→05Assertion (A) & Reason (B) MCQ
4 Q→06Case study (4 Marks)
2 Q→Sample Questions
MODEL PAPER 2025 questions
One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
Eco R1 cuts the DNA between bases G and A only when the sequence of GAATTC is present. The number of nucleotides present in the resultant sticky ends that will be formed in each of the two strands of DNA after this enzyme cuts the DNA will be:
| Vector DNA | Foreign DNA | |
| A | 1 & 5 | 5 &1 |
| B | 2 & 4 | 4 &2 |
| C | 2 & 5 | 5 & 2 |
| D | 3 & 4 | 4 & 3 |
Adaptive radiation leads to which of the following?
- AIncreased competition among species
- BDecreased speciation rates
- CLimited morphological diversity among species
- ✓Rapid divergence of traits among populations inhabiting a given geographical area.
Answer: D.
View full solution →Idli – dosa dough rises due to production of which of the following gas?
- ACO
- ✓$CO _2$
- CNO
- D$NO _2$
Answer: B.
View full solution →The following diagram shows a fragment of DNA which is going to be transcribed, the upper strand with polarity 3’ to 5’ is the template strand:
3´ ATTGCC 5´
5´ TAACGG 3´
After transcription the mRNA can be represented by:
3´ ATTGCC 5´
5´ TAACGG 3´
After transcription the mRNA can be represented by:
- A5´ AUUGCC 3´
- B5´ AUUGCC 3’
- ✓5´ UAACGG 3´
- D5´ GGCAAU 3´
Answer: C.
View full solution →$(i)$ Assume that, $ \text{GPP}$ Forest $A = \text{GPP}$ Forest $B = \text{GPP}$ Forest $C,$ If Forest $A$ has $ \text{NPP} = 1254 J/m^2/day;$ Forest $B, \text{NPP} =2157 J/m^2/day;$ and Forest $C, \text{NPP} = 779 J/m^2/day,$ which one of these forests has maximum energy loss by respiration? Give reason.
$(ii)$ Draw an ecological pyramid of number of the following food chains
$a.$ Grass$-$Animal$-$Fleas on the host animal
$b.$ Tree $-$ Insects $-$ Woodpecker
View full solution →$(ii)$ Draw an ecological pyramid of number of the following food chains
$a.$ Grass$-$Animal$-$Fleas on the host animal
$b.$ Tree $-$ Insects $-$ Woodpecker
$(i)$ It was estimated that if an evergreen forest has a $ \text{GPP} $ of $400 J/m^2/day$ and $150 J/m^2/day$ worth of carbon dioxide flows out of that forest, what is the $ \text{NPP} $ in that forest?
$(ii)$ Explain why pyramids of energy must always be upright.
View full solution →$(ii)$ Explain why pyramids of energy must always be upright.
A culture plate of Lactobacillus shows blue-coloured colonies and colourless colonies. Explain the principle involved in the formation of such variance in the colour of colonies.
Given below is the relationship between the HIV levels in the blood and helper T cell count in a person detected with AIDS. Study the relationship and answer the questions that follow.
A. What kind of relationship is observed in the virus levels and the immune response after some days of the initial infection?
B. Does it completely clear the virus from the body permanently? Give reason for your answer.
A. What kind of relationship is observed in the virus levels and the immune response after some days of the initial infection?
B. Does it completely clear the virus from the body permanently? Give reason for your answer.
Given below is a schematic representation of a mRNA strand
(i) In the above sequence identify the translational unit in mRNA.
(ii) Where are UTRs found and what is their significance?
(i) In the above sequence identify the translational unit in mRNA.
(ii) Where are UTRs found and what is their significance?
A. Diagram given below depicts different species of Warbler birds feeding on different regions on a Spruce tree. Explain the mechanism which helps them to co-exist.
B. What does Gause's exclusion principle state? Does it apply in the case shown above? Explain.
B. What does Gause's exclusion principle state? Does it apply in the case shown above? Explain.
Explain how PCR technique can be used for amplification of a small amount of DNA template.
Bio-fertilisers are organisms that enrich the nutrient quality in the soil. Explain the role of three main sources of bio-fertilisers.
Describe the steps involved in Southern blot hybridization using radiolabeled VNTR as a probe.
The schematic representation given below shows the concept of Central Dogma.
A. During the process of replication and transcription the pairing of
nitrogenous bases is not similar. Explain.
B. How is the above process modified in a retrovirus? Name the process.
C. Justify why during the process of transcription only a segment of DNA is copied into RNA.
A. During the process of replication and transcription the pairing of
nitrogenous bases is not similar. Explain.
B. How is the above process modified in a retrovirus? Name the process.
C. Justify why during the process of transcription only a segment of DNA is copied into RNA.
B.
(i) Name the two types of desirable approaches to conserve biodiversity? Explain with examples bringing out the difference between the two types.
(ii) State the features of a stable biological community?
(i) Name the two types of desirable approaches to conserve biodiversity? Explain with examples bringing out the difference between the two types.
(ii) State the features of a stable biological community?
B. In the future, genetic therapies may be used to prevent, treat, or cure certain inherited disorders in humans. Justify the statement with a suitable example.
(i) Explain the significance of each of the following features present in plants given below:, (a) In rose-bay plant the stamens ripen before the stigma., (b) In certain species of primrose, the flowers have short stamen and long style., (c) The bisexual flower of mustard exhibits rejection of self-pollen grain., (ii) Explain how autogamy is prevented in castor and papaya plant respectively.
A.
(i) Why is there a need to conserve biodiversity? (Any two reasons)
(ii) Name and explain any two causes that are responsible for the loss of biodiversity.
(i) Why is there a need to conserve biodiversity? (Any two reasons)
(ii) Name and explain any two causes that are responsible for the loss of biodiversity.
A. Explain how advent of biotechnology has helped in preventing infestation by nematodes and thereby increasing crop yield.
Assertion (A): DNA fragments can be isolated by Gel electrophoresis on the basis of their size.
Reason (R): The larger the fragment size, the faster it moves.
Reason (R): The larger the fragment size, the faster it moves.
- ABoth A and R are true and R is the correct explanation of A.
- BBoth A and R are true and R is not the correct explanation of A.
- ✓A is true but R is false.
- DA is False but R is true.
Answer: C.
View full solution →Assertion (A): A floating cover placed over the slurry in a biogas plant keeps on rising.
Reason (R): This cover keeps on rising due to the gas produced in the tank by the microbial activity.
Reason (R): This cover keeps on rising due to the gas produced in the tank by the microbial activity.
- ABoth A and R are true and R is the correct explanation of A.
- BBoth A and R are true and R is not the correct explanation of A.
- CA is true but R is false.
- DA is False but R is true.
Assertion (A): Deoxyribonucleoside triphosphates serve dual purposes.
Reason (R): They act as proof readers and provide energy.
Reason (R): They act as proof readers and provide energy.
- ABoth A and R are true and R is the correct explanation of A.
- BBoth A and R are true and R is not the correct explanation of A.
- ✓A is true but R is false.
- DA is False but R is true.
Answer: C.
View full solution →Assertion (A): Cells of tapetum have more than one nucleus.
Reason (R): They undergo meiosis without cytokinesis.
Reason (R): They undergo meiosis without cytokinesis.
- ABoth A and R are true and R is the correct explanation of A.
- BBoth A and R are true and R is not the correct explanation of A.
- ✓A is true but R is false.
- DA is False but R is true.
Answer: C.
View full solution →Given below is the pattern of temperature in a person suffering from a non-viral disease transmitted by mosquitoes. Study the graph and answer the questions that follow:
A. Explain the factor(s) responsible for this pattern of temperature.
B. How does this pathogen multiply in the human body?
C. How is this infection transmitted to humans?
OR
D. Which stages of the life cycle of this pathogen are completed in the mosquito's gut?
A. Explain the factor(s) responsible for this pattern of temperature.
B. How does this pathogen multiply in the human body?
C. How is this infection transmitted to humans?
OR
D. Which stages of the life cycle of this pathogen are completed in the mosquito's gut?
Assuming that within a population of beetles where Hardy Weinberg conditions are met, the colour black $(B)$ is dominant over the colour red $(b). 40\%$ of all beetles are red $(bb).$
Given this information, answer the questions below:
$A.$ What is the frequency of red beetles?
$B.$ Calculate is the percentage of beetles in the population that are heterozygous.
$C.$ What is the frequency of homozygous dominant individuals?
$OR$
$D.$ Assuming that Hardy Wienberg conditions are met in the beetle population consisting of $1500$ beetles. How many beetles would you expect to be black and red in colour respectively?
View full solution →Given this information, answer the questions below:
$A.$ What is the frequency of red beetles?
$B.$ Calculate is the percentage of beetles in the population that are heterozygous.
$C.$ What is the frequency of homozygous dominant individuals?
$OR$
$D.$ Assuming that Hardy Wienberg conditions are met in the beetle population consisting of $1500$ beetles. How many beetles would you expect to be black and red in colour respectively?
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